Diagnostic article Generic OBD-II
P0786: Shift-timing solenoid current error under a stable command
P0786 evaluates current error in the SLS timing-solenoid circuit under qualified, stable conditions.
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Documented application
2009 General Motors diagnostic parameter file 09OBDG05 TRANS Diagnostics.pdf. Section-specific modules and calibrations; no per-code model or engine applicability established.
The code alone does not identify a failed part or establish that a vehicle is safe to drive. Confirm the vehicle, reporting module and applicable service procedure.
GM's group 05 transmission table assigns P0786 to a terminal-short diagnostic for the SLS timing solenoid. The generic range/performance label therefore needs the context of this electrical current check. The monitor is not simply measuring how long a gear change takes.
Stable current demand makes the comparison meaningful
The source specifies current error above 80 mA while the output-current target remains above its calibrated level and unchanged during detection. System voltage must be within its window and sufficiently stable, and oil temperature must exceed 20°C. Those conditions reduce ambiguity in the target-versus-response comparison.
The listed evaluation lasts 2.75 seconds with emergency mode inactive and the diagnostic state enabled. Transmission-temperature circuit faults also inhibit the check. A reading obtained outside that window cannot be treated as the same test.
Separate it from shift-time monitoring
The adjacent P0780 entry evaluates excessively long, short or tied-up shifts. P0786 concerns the timing-solenoid electrical path. A shift complaint does not replace the current evidence required for this code.
Use the exact transmission procedure to identify SLS and interpret the current measurement. The table does not establish a connector pin or automatic replacement. Verification should demonstrate credible current tracking and completed monitoring under qualified conditions, followed by any separate functional checks required by the service procedure.
Source and applicability
2009 General Motors diagnostic parameter file 09OBDG05 TRANS Diagnostics.pdf. Section-specific modules and calibrations; no per-code model or engine applicability established. This explanation describes the documented monitor, not a universal repair procedure.
Article source documents
Source checks describe how the text was prepared; they do not certify a diagnosis or confirm compatibility with every vehicle using this code.
Original code reference
Dictionary definition
Shift Timing Solenoid A Range/Performance
This definition retains its original catalog scope. The article above is limited to its explicitly documented application.
Reference scope
Generic OBD-II definition.
A manufacturer label does not establish the model, year, engine or module to which a diagnosis applies. Read the safety and diagnostic limits.
Definition source
- DTC Database: pinned community code definitions
Source checked · MIT